Dual ... A keyword for modeling the brain

Dual representation
Dual working
Dual neurons
Dual ....
These days it seems Brain modelers are more interested in using dual things in their models and interestingly by using this word, they have got good results.
Here are some examples of some works around the world:

• USA: Professor Ron Sun's cognitive architecture, He's used dual representation of the brain to build a cognitive modeling software, CLARION. He was so successful in creating creativity in hardware(one of my two last posts was about this.)
  

• Turkey: Professor A. Khashman's published an article recently (A Khashman - Neural Networks, Dec 2010 - Elsevier). He's used a novel emotional dual neural network architecture in face recognition and he got much better results than other models.
  

• Iran: Professor Majid Nili AhmadAbadi: Recently, In AmirKabir cognitive science seminars he talked about good results comes by combining two models and used a dual... I searched the article he talked about but I didn't find it. This article seems to be another successful dual model he works on.
  

I've searched the net to find a theory about what exactly this dual is, and I found Dual-Coding theory.
Maybe the parallel nature of processes in the brain and the relation between different parts of the brain makes this dual works well.
Maybe triplex, foursome, quintuplet, .... works better, betterer,bettererer,... :)